Field of the Invention
The present invention relates to a cleaning unit, to an image bearing unit including the cleaning unit, and to an image forming apparatus including the cleaning unit.
Description of the Related Art
An electro-photographic image forming apparatus is configured to form an image by transferring a toner image formed on an image bearing unit such as a photosensitive drum, intermediate transfer body etc., onto a recording medium such as a sheet of paper, plastic etc.
Conventionally, the image forming apparatus such as one disposed in Japanese Patent Application Laid-open No. 2006-139084 (see FIG. 8 thereof) for example is configured to remove unused toner left on the image bearing unit by a cleaning blade 525 and to recover the toner within a drum cartridge 600. The recovered toner is conveyed by a toner conveying member installed near the cleaning blade 525 to a waste toner container (recovered toner box) outside of the drum cartridge from an aspect of prolonging a life of the process cartridge.
As a toner conveyer member, there is a case of adopting a toner conveying screw formed into a cylindrical (spring) shape by spirally winding a metallic wire rod (for instance, a screw 622 in Japanese Patent Application Laid-open No. 2006-139084). This toner conveying screw is disposed within a cylindrical toner conveying path and is rotationally driven by a driving system, e.g., a screw gear 526 in the abovementioned disclosure. As for the rotational driving force of the toner conveying member of this sort, there is a case of transmitting a rotational driving force from a driving system rotationally driving a photosensitive drum within a drum cartridge through a drum gear, besides using an independent driving source.
Although there is also known a screw type toner conveying member in which a blade is molded spirally around a center shaft (metallic or resin-made), the screw formed into the cylindrical shape by the spring as described above has advantages over the conventional one in that it enables to downsize, lighten, simplify, and lower the cost of the toner conveyer unit.
In connecting the driving system (screw gear) with the cylindrical (spring) screw, i.e., the toner conveying member, to transmit the driving force to the toner conveying member, there is a case of using a support structure of axially supporting the toner conveying member by tensioning from both ends of the toner conveying member, similarly to the case of the screw having the center shaft.
However, conventionally, a structure of connecting the driving system (screw gear) rigidly and integrally with the toner conveying screw even if the toner conveying screw is formed of the cylindrical (spring) screw is often adopted. Then, if the cylindrical (spring) screw generates vibration in such conventional structure, the vibration is transmitted to the driving system (screw gear).
Here, a possible factor of the vibration of the toner conveying screw is a reaction force received by the screw when the screw conveys recovered toner within a drum cartridge. This reaction force can be decomposed into a force mainly in a toner conveying direction (expansion direction) and a force in a screw rotating direction (twist direction).
If the screw vibrates due to the reaction force and the vibration is transmitted to the image bearing unit, it is not preferable because the image bearing unit may vibrate. Accordingly, a configuration that can reduce vibration energy transmitted from the screw to the image bearing unit is required.